discourse/lib/encodings.rb

# frozen_string_literal: true

require "rchardet"

module Encodings
  def self.to_utf8(string)
    result = CharDet.detect(string)

    encoded_string = try_utf8(string, result["encoding"]) if result && result["encoding"]
    encoded_string = force_utf8(string) if encoded_string.nil?
    encoded_string
  end

  def self.try_utf8(string, source_encoding)
    encoded = string.encode(Encoding::UTF_8, source_encoding)
    encoded&.valid_encoding? ? delete_bom!(encoded) : nil
  rescue Encoding::InvalidByteSequenceError,
         Encoding::UndefinedConversionError,
         Encoding::ConverterNotFoundError
    nil
  end

  def self.force_utf8(string)
    encoded_string = string.encode(Encoding::UTF_8, undef: :replace, invalid: :replace, replace: "")
    delete_bom!(encoded_string)
  end

  def self.delete_bom!(string)
    string.presence&.sub!(/\A\xEF\xBB\xBF/, "")
    string
  end
end